Create the wvdial config file

• The next step is to create a config file for wvdial so you can connect to your service provider.
• Open a terminal window and enter:

sudo leafpad /etc/wvdial.conf

• Replace the content of the file with the following.

[Dialer 3gconnect]
Init1 = ATZ
Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
Init3 = AT+CGDCONT=1,"IP","internet"
Stupid Mode = 1
Modem Type = Analog Modem
ISDN = 0
Phone = *99#
Modem = /dev/gsmmodem
Username = { }
Password = { }
Baud = 460800

• Replace internet with your service provider’s APN
• Replace the Phone number if you need to dial a different code to connect.
• Replace Username and Password if needed. To leave the username and password as blank use { }

Source: How to setup a USB 3G Modem on Raspberry PI using usb_modeswitch and wvdial | How To | The Fan Club | dynamic design solutions